The 3d model of MC Escher's "Relativity" I made as an homage, free to download and use!
It is offered without materials, partly due to not being sure about redistributing some of the textures used.

The model is available in the following formats
Maya ASCII - Should load in most versions of Maya, maintains proper grouping, etc.
OBJ - This is offered 'as is' and without support, it tested fine in Blender, albeit a bit small...
These are archived in .Zip format.

Escher's "Relativity" model released under full details listed in 'LicenseAndInfo' text file.